Blinking of eyes excessively.

Good that you already got the referral, just go for the KKH appointment, don't wait. My neighbour brought her son there for something similar and the paediatric ophthalmologist was thorough, checked for everything from early myopia to allergies to muscle issues, so you'll get a much clearer picture than a GP can give. Some mums I know found it was just allergies causing the squinting, but a couple had kids who turned out to need glasses earlier than expected, so it's really worth ruling everything out properly. Definitely follow through with the specialist rather than leaving it, four days of persistent blinking is worth a proper eye check.